Knit with strips without barbs, method of making same and prostheses made from said knit

ABSTRACT

The present invention relates to an openwork prosthetic knit ( 1 ) made from a single piece based on at least a first yarn made of biocompatible polymer material that defines a first face ( 2 ) and a second face that are opposite one another and from a second biocompatible yarn that generates barbs ( 5 ) that protrude outwards from at least said first face, characterized in that said first face comprises at least one longitudinal strip ( 4 ) in the direction of the manufacture of said knit, over which it is provided with said barbs ( 5 ), and at least one longitudinal strip ( 3 ) in the direction of the manufacture of said knit, over which it is free of such barbs. It also relates to a process for manufacturing such a knit ( 1 ) and to a prosthesis comprising such a knit ( 1 ).

The present invention relates to a prosthetic knit made from a singlepiece, at least one face of which comprises one or more strips providedwith barbs and one or more strips free of barbs. Such a knit canparticularly be used for producing prostheses requiring variablefastening capabilities, for example for fastening to biological tissues,on the surface of said prosthesis.

Wall reinforcement prostheses, for example for the abdominal wall, arewidely used in surgery. These prostheses are intended to treat herniasby temporarily or permanently filling a tissue defect. These prosthesesare generally made of biocompatible prosthetic fabric and can have anumber of shapes, for example rectangular, circular or oval, dependingon the anatomical structure to which they are to be fitted. Some ofthese prostheses are made from entirely bioresorbable yarns and areintended to disappear after having performed their reinforcing rolewhile cell colonization takes place and tissue rehabilitation takesover. Others comprise non-bioresorbable yarns and are intended to remainpermanently in the body of the patient.

Some of these prostheses are made from an arrangement of yarns, a knit,a woven or non-woven fabric, comprising barbs protruding outwards fromone face of the prosthesis: these barbs constitute hooks that are ableto fix themselves either in another prosthetic fabric, belonging to thesame prosthesis or not, or directly in the biological tissues, forexample the abdominal wall.

The presence of barbs capable of fastening directly to biologicaltissues makes it possible to do away with additional means of attachmentfor the prosthesis, such as staples, sutures, etc. However, in certaincases, for example when the prosthesis must be implanted in the vicinityof fragile or sensitive organs, such as vessels, nerves, or else thespermatic cord, it may prove advantageous for the part of the prosthesisin contact with these organs to be free of such barbs.

In such cases, a composite prosthesis is generally produced comprising afirst textile portion with barbs and a second textile portion withoutbarbs that is assembled to the first portion, for example by means ofstitching, or ultrasonic welding, etc. Such a process is tedious andcomplicated. Furthermore, due to the discontinuous nature of the textilemaking up the composite prosthesis thus obtained, the mechanicalproperties of the prosthesis are not the same over the whole of theprosthesis. In particular, the assembly zone of the first textileportion to the second textile portion generally constitutes a line ofweakness of the prosthesis.

Therefore, there remains a need for a knit that makes it possible toprovide a reinforcing prosthesis both with zones that have goodfastening capabilities and smoother and non-traumatizing zones, andwhich would not require additional steps during its manufacturingprocess.

The present invention aims to meet this need by proposing a knit made ofa single piece, at least one face of which has one or more longitudinalstrips provided with barbs and one or more longitudinal strips free ofsuch barbs.

The present invention relates to an openwork prosthetic knit made from asingle piece based on at least a first yarn made of biocompatiblepolymer material that defines a first face and a second face that areopposite one another and from a second biocompatible yarn that generatesbarbs that protrude outwards from at least said first face,characterized in that said first face comprises at least onelongitudinal strip in the direction of the manufacture of said knit,over which it is provided with said barbs, and at least one longitudinalstrip in the direction of the manufacture of said knit, over which it isfree of such barbs.

The present invention also relates to a process for manufacturing a knitsuch as above comprising the following steps:

a) manufacture of an arrangement of first yarns of biocompatible polymermaterials that define a first face and a second face that are oppositeone another for said knit and of at least one second yarn, biocompatibleheat-fusible monofilament yarn, that forms small loops that protrudeoutwards from said first face, by knitting on a warp or Raschel knittingmachine, of said first yarns and of said second yarn using at leastthree guide bars, said first yarns being threaded, continuously on twoof said three guide bars, over the whole of the width of said knittingmachine, said second yarn being threaded, intermittently on the thirdguide bar, only over a width corresponding to the width of the strip(s)provided with barbs of said knit,

b) cutting, by melting, of said loops, each loop generating two barbs.

Step b) of melting the loops of the above process is described forexample in document WO01/81667.

In the present application, the expression “prosthetic knit” isunderstood to mean a knit intended to be implanted in the human oranimal body in the form of a prosthesis or of any other part made atleast partly with said knit.

In the present application, the expression “openwork knit” is understoodto mean a knit having a weave or weaves that determine cells or voids inthe thickness of the knit and on the faces of the knit, these cells orvoids possibly forming channels that open on both sides of the knit.Such an openwork knit enables better tissue integration.

The expression “knit made from a single piece” is understood accordingto the present application to mean that the knit is produced in a singleknitting step and does not comprise additional textile added by anymeans of attachment such as stitching, ultrasonic welding, etc. Thus,the knit according to the invention has mechanical properties that areconstant over the whole of its surface, independently of the presence orabsence of barbs on the longitudinal strips.

The first yarns of the knit according to the invention may bemonofilament and/or multifilament yarns, and may be made from anybiodegradable or non-biodegradable biocompatible material. Thus, thebiodegradable materials suitable for the first yarns of the knit of thepresent invention may be selected from polylactic acid (PLA),polyglycolic acid (PGA), oxidized cellulose, polycaprolactone (PCL),polydioxanone (PDO), trimethylene carbonate (TMC), polyvinyl alcohol(PVA), polyhydroxyalkanoates (PHAs), copolymers thereof and mixturesthereof. The non-biodegradable materials suitable for the first yarns ofthe knit of the present invention may be selected from polyethyleneterephthalate (PET), polyamides, aramids, expandedpolytetrafluoroethylene, polyurethane, polyvinylidene difluoride (PVDF),butyl ester polymers, polyetheretherketone (PEEK), polyolefins (such aspolyethylene or polypropylene), polyethers, copper alloys, silver orplatinum alloys, medical grades of steel such as medical-grade stainlesssteel, and combinations thereof.

In one embodiment of the invention, said first face comprises several ofsaid longitudinal strips provided with barbs that protrude outwards, andseveral of said longitudinal strips which are free of such barbs.

In the longitudinal strip(s) where they are present, the barbs of theknit according to the invention may protrude from the first facesubstantially perpendicular to the plane of said face or alternativelyalong one or more planes that are inclined relative to the plane of saidface. Generally, these barbs have the shape of a shaft, having thediameter of the yarn used for their formation, surmounted by a headhaving a diameter greater than that of the shaft.

For example, the first face of the knit according to the invention maycomprise several longitudinal strips free of barbs, these strips beingintended to be located opposite fragile or sensitive organs once theprosthesis or knit is implanted, the remainder of the first face of theknit being provided with barbs located opposite other organs, forexample muscles, to which they will be able to fasten in order to attachthe knit or the prosthesis.

Alternatively, these barbs may be intended to be entangled in one ormore arrangements of yarns, fibres, filaments and/or multifilaments ofanother prosthetic textile, for example in order to form a compositereinforcing prosthesis, in particular if it is desired, for example, foronly certain strips of the knit according to the invention to fasten inthis other prosthetic textile.

Thus, it is possible to prepare knits having a central longitudinalstrip free of barbs, and two lateral longitudinal strips provided withbarbs. It is for example possible to cut out transversely in such a knitprostheses for the manufacture of bands for treating urinaryincontinence in women, such bands having a relatively smooth andatraumatic central portion for placing opposite the urethra, andcorresponding to the central longitudinal strip of the knit during themanufacture thereof before cutting, and two outermost portions withbarbs for attachment to the surrounding tissues, these two outermostportions of the prosthesis corresponding to the two lateral longitudinalstrips of the knit during the manufacture thereof before cutting.

In one embodiment, the second yarn is a heat-fusible monofilament yarn.Thus, the step of manufacturing the barbs is facilitated, as will becomeapparent from the description that follows. In particular, in oneembodiment, said barbs protrude outwards from said first face over alength ranging from 1 to 2 mm, preferably over a length of around 1.5mm. Such a length of the barbs enables both a good fastening of thebarbs to the biological tissues and an optimized manufacturing process.Such a length of the barbs makes it possible in particular to preservethe integrity of the yarns forming the knit during the formation of thebarbs by melting of the loops as described in WO01/81667.

In one embodiment of the invention, said second yarn is a monofilamentyarn made of polylactic acid.

In one embodiment of the invention, the width of the longitudinalstrip(s) free of barbs varies from 1 cm to 3 cm. Such embodiments allowa facilitated and optimized manufacturing process. Such a small widthmakes it possible in particular to preserve the integrity of the yarnsforming the knit during the step of melting the loops in order to obtainthe barbs as described in WO01/81667.

In one embodiment of the invention, the chart followed for the knittingof said first and second yarns is selected from the following charts:

for said first yarns, threaded on two guide bars B1 and B2, according tothe ISO 11676 standard:

-   -   bar B1: 1.0/0.1//    -   bar B2: 1.0/5.5/1.0/3.3// or 1.0/7.7/6.6/7.7//

for said second yarn, threaded on the third guide bar B3, according tothe ISO 11676 standard:

-   -   bar B3: 2.1/5.5/3.4/0.0//

In embodiments, the first yarns are made of polyethylene terephthalate,and the second yarn is made of of polylactic acid.

For example, the second yarn may be threaded intermittently according tothe following threading plan: (1 full-3 empty)×60, 1 full, 19 empty, (1full-3 empty)×60. Alternatively, the second yarn may be threadedintermittently according to the following threading plan: (1 full-3empty)×60, 1 full, 15 empty, (1 full-3 empty)×60. Alternatively, thesecond yarn may be threaded intermittently according to the followingthreading plan: (1 full-3 empty)×60, 1 full, 11 empty, (1 full-3empty)×60.

The advantages of the present invention will emerge from the followingexamples and from the figures in which:

FIGS. 1A to 1C show the respective charts of three guide bars used forobtaining a knit according to the invention,

FIG. 2 is a partial top view of a knit according to the invention,

FIG. 3 is a cross section of the knit from FIG. 2.

EXAMPLES Example 1

The following knit according to the invention is produced on a warpknitting machine:

Knit A: having the following chart according to the ISO 11676 standard:

bar B1: 1.0/0.1//

bar B2: 1.0/5.5/1.0/3.3//

bar B3: 2.1/5.5/3.4/0.0//

The respective charts for bars B1, B2 and B3 are illustrated in FIGS. 1Ato 1C.

Alternatively, the chart of bar B2 could be replaced by the following:1.0/7.7/6.6/7.7//

Bar B1 and bar B2 are each threaded continuously 1 full, 1 empty, overthe width of the knitting machine with a monofilament yarn made ofpolyethylene terephthalate (PET) having a diameter of 0.08 mm,commercially available from the company SIDER ARC.

Bar B3, which will give rise to the barbs, is threaded intermittentlywith a heat-fusible monofilament yarn made of polylactic acid having adiameter of 0.15 mm, according to the following threading plan:

(1 full-3 empty)×60, 1 full, 19 empty, (1 full-3 empty)×60

The knitting according to the chart above leads to the formation ofloops that protrude outwards from one face of the knit by theheat-fusible monofilament made of polylactic acid.

The knit 1 obtained, after cutting the loops by melting as described inWO01/81667 in order to obtain barbs, is shown in FIGS. 2 and 3: thefirst face, namely the top face 2 in FIGS. 2 and 3, has a centrallongitudinal strip 3 in the direction EE′ of the manufacture of saidknit 1, on which it is free of barbs and two lateral strips 4 providedwith barbs 5. Generally the barbs 5 have the shape of a shaft having thediameter of the yarn used for their formation, surmounted by a headhaving a diameter greater than that of the shaft. The barbs 5 protrudeoutwards from the first face 2 over a length of around 1.5 mm. Such alength of the barbs 5 enables a good fastening of the barbs in thebiological tissues during the implantation of the knit 1 or of aprosthesis comprising this knit 1. Furthermore, such a length of thebarbs 5 makes it possible in particular to preserve the integrity of themonofilament yarns made of polyethylene terephthalate (PET) forming theknit 1 during the formation of the barbs by melting the loops asdescribed in WO01/81667, the hotplate used for melting the loops thusbeing kept at a sufficient distance from the monofilament yarns made ofpolyethylene terephthalate (PET) that form the ground structure of theknit 1.

The central longitudinal strip 3 has a width of around 1.8 cm. Such asmall width makes it possible to preserve the integrity of themonofilament yarns made of polyethylene terephthalate (PET) forming theground structure of the knit 1 during the step of melting the loops inorder to obtain the barbs 5.

Thus, the heat-fusible monofilament yarn is threaded on the bar B3, onlyover a width corresponding to the sum of the widths of the two lateralstrips 4 provided with barbs 5 of said knit 1.

Such a knit 1 has the same mechanical properties as the knit which wouldbe obtained if the heat-fusible monofilament yarn was threadedcontinuously 1 full, 3 empty, on the bar B3 over the total width of theknitting machine.

Example 2

A knit is produced with the same yarns and charts as those from EXAMPLE1, the knit according to the present example differing from that ofEXAMPLE 1 only by the threading of the bar B3, this threading being:

(1 full-3 empty)×60, 1 full, 15 empty, (1 full-3 empty)×60

The knit obtained, after cutting the loops by melting as described inWO01/81667 in order to obtain barbs, is similar to that from FIGS. 2 and3, but with a narrower central strip. In the present example, the firstface of the knit has a central longitudinal strip in the direction ofthe manufacture of said knit, on which it is free of barbs, having awidth of around 1.4 cm. Such a small width makes it possible to preservethe integrity of the monofilament yarns made of polyethyleneterephthalate (PET) that form the ground structure of the knit duringthe step of melting the loops in order to obtain the barbs.

Such a knit has the same mechanical properties as the knit which wouldbe obtained if the heat-fusible monofilament yarn was threadedcontinuously 1 full, 3 empty, on the bar B3 over the total width of theknitting machine.

Example 3

A knit is produced with the same yarns and charts as those from EXAMPLE1, the knit according to the present example differing from that ofEXAMPLE 1 only by the threading of the bar B3, this threading being:

(1 full-3 empty)×60, 1 full, 11 empty, (1 full-3 empty)×60

The knit obtained, after cutting the loops by melting as described inWO01/81667 in order to obtain barbs, is similar to that from EXAMPLE 2,but with an even narrower central strip. In the present example, thefirst face of the knit has a central longitudinal strip in the directionof the manufacture of said knit, on which it is free of barbs, having awidth of around 1 cm. Such a small width makes it possible to preservethe integrity of the monofilament yarns made of polyethyleneterephthalate (PET) that form the ground structure of the knit duringthe step of melting the loops in order to obtain the barbs.

Such a knit has the same mechanical properties as the knit which wouldbe obtained if the heat-fusible monofilament yarn was threadedcontinuously 1 full, 3 empty, on the bar B3 over the total width of theknitting machine.

The knits from Examples 1 to 3 above may be used as they are or incombination with other textiles in order to form reinforcing prostheses,for example abdominal wall reinforcing prostheses, or else bands fortreating urinary incontinence.

1-12. (canceled)
 13. An openwork prosthetic knit comprising a singlepiece based on at least a first yarn made of biocompatible polymermaterial that defines a first face and a second face that are oppositeone another and from a second biocompatible yarn that generates barbsthat protrude outwards from at least said first face, wherein said firstface comprises at least a first longitudinal strip in a direction of themanufacture of said knit, over which the first longitudinal strip isprovided with said barbs, and at least a second longitudinal strip insaid direction of the manufacture of said knit, over which the secondlongitudinal strip is free of said barbs.
 14. The openwork prostheticknit according to claim 13, wherein said first face comprises several ofsaid first longitudinal strips provided with said barbs, and several ofsaid second longitudinal strips which are free of said barbs.
 15. Theopenwork prosthetic knit according to claim 13, wherein said second yarnis a heat-fusible monofilament yarn.
 16. The openwork prosthetic knitaccording to claim 13, wherein the first yarn comprises polyethyleneterephthalate and the second yarn comprises polylactic acid.
 17. Theopenwork prosthetic knit according to claim 13, wherein said barbsprotrude outwards from said first face over a length ranging from 1 to 2mm.
 18. The openwork prosthetic knit according to claim 13, wherein thesecond longitudinal strip free of said barbs comprises a width from 1 cmto 3 cm.
 19. The openwork prosthetic knit according to claim 13, whereinsaid barbs protrude from said first face substantially perpendicular toa plane of said first face.
 20. The openwork prosthetic knit accordingto claim 13, wherein said barbs protrude along one or more planes thatare inclined relative to a plane of said first face.
 21. The openworkprosthetic knit according to claim 13, wherein the knit furthercomprises a three guide bar knit construction with a guide bar pattern,according to the ISO 11676, of first guide bar B1: 1.0/0.1// secondguide bar B2: 1.0/5.5/1.0/3.3// or 1.0/7.7/6.6/7.7// third guide bar B3:2.1/5.5/3.4/0.0//
 22. The openwork prosthetic knit according to claim21, wherein the first yarn follows the pattern of the first and secondguide bars.
 23. The openwork prosthetic knit according to claim 22,wherein the first guide bar and the second guide bars are threadedcontinuously with the first yarn.
 24. The openwork prosthetic knitaccording to claim 21, wherein the second yarn follows the pattern ofthe third guide bar.
 25. The openwork prosthetic knit according to claim24, wherein the third guide bar is threaded intermittently with thesecond yarn according to a threading plan: (1 full-3 empty)×60, 1 full,19 empty, (1 full-3 empty)×60.
 26. The openwork prosthetic knitaccording to claim 24, wherein the third guide bar is threadedintermittently with the second yarn according to a threading plan: (1full-3 empty)×60, 1 full, 15 empty, (1 full-3 empty)×60.
 27. Theopenwork prosthetic knit according to claim 24, wherein the third guidebar is threaded intermittently with the second yarn according to athreading plan: (1 full-3 empty)×60, 1 full, 11 empty, (1 full-3empty)×60.
 28. The openwork prosthetic knit according to claim 13,wherein the knit further comprises first zones that have fasteningcapabilities and second zones that are smooth and non-traumatizing.